Concept of hydraulic porosity and experimental investigation in nonlinear flow analysis through Rubble-mound breakwaters

• We determine coefficients of non-linear equation governing unsteady turbulent flow.
• We determine flow velocity and power of the porosity term may be a variable.
• The hydraulic porosity depending upon the nature of the flow regime.
• We fit an extended regression model in steady state and unsteady flow.
• The proposed equation is a more reliable tool for engineering applications.

SummaryThis paper aims to cast light on findings of experimental results and theoretical findings that evaluate hydraulic coefficients for non-linear flow through coarse aggregates. Experimental pilot made use of a physical model consisting of a flume of 13 m in length, being controlled by an electro-mechanical device to create different types of flow regimes. In this regard, two different relatively uniform aggregates ranging in size from 2 to 19 mm at first and 2 to 25 mm at second materials have been selected. The physical characteristics such as size distribution, porosity and fluid viscosity have been measured for each material. To create a set of the reliable hydraulic gradient vs. bulk velocity data, tests have been conducted on the materials. A non-linear mathematical model based on the extended Forchheimer’s equation (EFE) has been employed in developing necessary equations needed for the assessments. Findings indicate: in determination of flow velocity within the pores of the media, the porosity term exponent may depend upon the nature of the flow regime. In addition, the proposed general equation for non-Darcy unsteady flow through coarse porous media seems to be a more reliable tool for modeling purposes and engineering applications.